A nice solution is that every developer adds lines or blocks to random places in a list or a file, but a better solution is to sort these lines (especially for lists like composer.json, translation files, etc…). This way you insert new lines in “random” places, keeping it clear for everyone how things are added.

Something that does not work for composer.json, but something I highly recommend, is to add trailing commas in PHP arrays and to not align code (see the blogpost by Made With Love about “How clean are your diffs?”). This eases up merging too!